of 1.99 U/mg. The enzymatic hydrolysis experiment of standard oligosaccharides showed that GH5-2339 was a bifunctional endo-β-1,4-glucanase/mannanase. Molecular docking and site-directed mutagenesis confirmed that S207, N247, and Y285 were critical for the catalytic activity of the enzyme. Furthermore, we established a method to prepare Bletilla striata oligosaccharides (BO) from Bletilla striata polysaccharides (BP) via biotransformation with GH5-2339-expressing recombinant Pichia pastoris. Using a membrane filtration system, we purified BO with a degree of polymerization ranging from 2 to 7. Structural analysis indicated that BO consists mainly of β-1,4-linked mannose and glucose. In vitro fermentation demonstrated the prebiotic potential of BO by promoting the growth of Lactococcus lactis and Clostridium beijerinckii and enhancing acetate and butyrate production. This study identified and characterized a novel glucomannan endo-enzyme GH5-2339 from Achatina fulica, and demonstrated its considerable potential for the efficient preparation of BO.
Huang et al. (Fri,) studied this question.